Dart compared to TypeScript

Examples for Dart code compared to TypeScript code.

You can easily try all Dart examples on https://dartpad.dartlang.org/ and TypeScript examples on http://www.typescriptlang.org/play/

Packages

---

TypeScript

package.json // NPM

Dart

pubspec.yaml // Pub

Comments

---

TypeScript

// single line comment
/* 
 multi line comment
*/

Dart

// single line comment
// 
// multi line comment
//
/// documentation comment

Logging

---

TypeScript

console.log('TypeScript code');

Dart

print('Dart code');

Basic types

---

TypeScript

const boolType: boolean = true;
const numberType: number = 5;
const stringType: string = 'John';
const arrayType: [] = [];
const anyType: any = 'John'; // Can be anything;
const tupleType: [string, number] = ['John', 5];

Dart

final bool boolType = true;
final int numberType = 5;
final double doubleType = 5.5;
final String stringType = 'John';
final List listType = [];
final dynamic dynamicType = 'John'; // Can be anything;

Variables

---

TypeScript

var a: string = 'a';
let b: string = 'b';
const c: string = 'c';

Dart

var a = 'a';
-
final String c = 'c'; // runtime constant
const c = 'c'; // compile time constant / freezing 

Interpolation

---

TypeScript

const firstName: string = 'John';
const lastName: string = 'Doe';

console.log(`This is ${firstName} ${lastName})

Dart

final String firstName = 'John';
final String lastName = 'Doe';

print('This is $firstName $lastName');

Arrays

---

TypeScript

const persons: string[] = ['John', 'William'];

Dart

final List<String> persons = ['John', 'William'];

Objects

---

TypeScript

const person = {
  name: 'John',
};

console.log(person.name)  // John

Dart

// As a map
Map person = {
  'name': 'John'
}

print(person['name']) // John

// As a class
class Person {
  String name = 'John';
}

var person = Person();
print(person.name) // John

Functions

---

TypeScript

function add(a: number, b: number): number {
  return a + b;
}

Dart

int add(int a, int b) {
  return a + b;
}

Async functions

---

TypeScript

async function add(a: number, b: number): number {
  return a + b;
}

Dart

Future<int> add(int a, int b) async {
  return a + b;
}

Classes

---

TypeScript

export class Foo {}

Dart/Flutter

class Foo extends StatelessWidget  {}
class Foo extends StatefulWidget  {}

Constructor

---

TypeScript

export class Foo {
    person: string;
    constructor(name) {
        this.person = name;
    }  
}

Dart/Flutter

class Foo {
  String person;
  Foo({ this.person })
}

Overwriting classes

---

TypeScript

export class Foo {
   constructor() {
     super()
   }
}

Dart/Flutter

class Foo  {
  Foo({Key key}) : super(key:key);
}

Working with JSON

TypeScript

const person = {
  name: "John Doe" 
}
// stringify
const personJson = JSON.stringify(person);
console.log(personJson); // '{ "name": "John Doe", "age": 33 }'

// parse
const personObject = JSON.parse('{ "name": "John Doe", "age": 33 }');
console.log(personObject.name) // John Doe

Dart/Flutter

import 'dart:convert';

Map person = {
  "name": "John Doe"
};

// stringify
var personJson = jsonEncode(person);
print(personJson); // '{ "name": "John Doe", "age": 33 }'

// parse
Map personMap = jsonDecode('{ "name": "John Doe", "age": 33 }');
print(personMap["name"]) // John Doe